A Sample Space Consists of Three Outcomes, X, Y, and Z

Multiple Choice

A sample space consists of three outcomes, X, Y, and Z. Which of the following could be a legitimate assignment of probabilities to the outcomes?

A) $P ( X ) = 0.3 \quad P ( Y ) = 0.6 \quad P ( Z ) = 0.9$
B) $P ( X ) = 0.3 \quad P ( Y ) = 0.2 \quad P ( Z ) = 0.5$
C) $P ( X ) = 0.3 \quad P ( Y ) = 0.3 \quad P ( Z ) = 0.3$
D) $P ( X ) = 0.7 \quad P ( Y ) = - 0.3 \quad P ( Z ) = 0.6$